Developing Tapestry requires the use of JDK 1.5.
Effectively, you should have the following tools:
IntelliJ is available to all Tapestry committers under their generous open-source policy. This is one of the perks of being invited as a committer.
Tapestry 5 is built by Maven 2.
You can build individual modules, or (from the root folder) build everything.